MOUNT WILSON SOLAR OBSERVATORY. 235 



to the construction of a two-story concrete building adjacent to the 

 Monastery. The building contains eight rooms and, so far as possible, 

 will be devoted to the night observers, those engaged in solar work 

 Uving in the Monastery itself. 



Much general repair work has been done and many improvements 

 to the instruments and buildings have been carried out. Several 

 retaining walls have been built on Mount Wilson to prevent washing 

 of some of the steeper slopes by the winter rains. 



AN ELECTRIC-POWER TRANSMISSION-LINE TO MOUNT WILSON. 



In the spring the Southern California Edison Company submitted a 

 proposal to extend a transmission line up Mount Wilson for the 

 supply of electric power to the Observatory and the hotel compan3^ 

 Terms of agreement were soon di'awn up and construction work was 

 begun in July. The Une is now well advanced and should be in operation 

 during the autumn. Since all of the electric motors used in connection 

 with the instruments operate on direct current, a large motor-generator 

 set has been installed in the power house to transform the alternating 

 current into direct. 



An abundance of electric power on the mountain will be of great 

 value to the Observatory, not only for the operation of the instruments, 

 but also for special investigations which involve the use of a powerful 

 spark or an electric furnace. Probably it will also be utilized to some 

 extent for domestic purposes at the Monastery. The present power 

 plant mil be maintained for use in emergencies and when the trans- 

 mission hne is out of service. The spectroheliograph and such other 

 instruments as require a very constant current will be operated from 

 the storage battery, this being charged by the motor-generator set. 



